Can you tell me how to sew my own sling?

Sew two pieces of coordinating fabric (about 22" wide and 60" long) right sides together along their long sides. Turn right sides out and press flat. Fold in half matching ends, measure and cut end according to the following sizes S=28 1/2" M=29 1/2" L=30 1/2". While still folded, fold in half the other way, then cut a curve with sides ending 3" shorter than the length you cut. (When you open the piece back up, your ends should look like a smile.) Make a French Seam to finish your sling: sew ends together, turn and press flat, sew to encase raw edge, then sew down flap. Congratulations, you just made a pouch sling. If you're totally lost, don't feel bad, just order a sling and leave the sewing to me. :)

There are lots of tutorials online for making pouch slings that actually show pictures with the directions, they may be helpful to you if you do try to make your own.